Thanks for pointing this out. I don't think tcon->ses can be null
here but might as well add the check in a consistent way to avoid
confusion and static checker warnings
On Sat, May 2, 2020 at 8:32 AM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> Hello Aurelien Aptel,
>
> The patch feeaec621c09: "cifs: multichannel: move channel selection
> above transport layer" from Apr 24, 2020, leads to the following
> static checker warning:
>
> fs/cifs/smb2pdu.c:149 smb2_hdr_assemble()
> error: we previously assumed 'tcon->ses' could be null (see line 133)
>
> fs/cifs/smb2pdu.c
> 120 shdr->ProcessId = cpu_to_le32((__u16)current->tgid);
> 121
> 122 if (!tcon)
> 123 goto out;
> 124
> 125 /* GLOBAL_CAP_LARGE_MTU will only be set if dialect > SMB2.02 */
> 126 /* See sections 2.2.4 and 3.2.4.1.5 of MS-SMB2 */
> 127 if (server && (server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU))
> 128 shdr->CreditCharge = cpu_to_le16(1);
> 129 /* else CreditCharge MBZ */
> 130
> 131 shdr->TreeId = tcon->tid;
> 132 /* Uid is not converted */
> 133 if (tcon->ses)
> ^^^^^^^^^
> Check for NULL.
>
> 134 shdr->SessionId = tcon->ses->Suid;
> 135
> 136 /*
> 137 * If we would set SMB2_FLAGS_DFS_OPERATIONS on open we also would have
> 138 * to pass the path on the Open SMB prefixed by \\server\share.
> 139 * Not sure when we would need to do the augmented path (if ever) and
> 140 * setting this flag breaks the SMB2 open operation since it is
> 141 * illegal to send an empty path name (without \\server\share prefix)
> 142 * when the DFS flag is set in the SMB open header. We could
> 143 * consider setting the flag on all operations other than open
> 144 * but it is safer to net set it for now.
> 145 */
> 146 /* if (tcon->share_flags & SHI1005_FLAGS_DFS)
> 147 shdr->Flags |= SMB2_FLAGS_DFS_OPERATIONS; */
> 148
> 149 if (server && server->sign && !smb3_encryption_required(tcon))
> ^^^^
> Unchecked dereference inside the function. There used to be a bunch
> of checks for NULL "tcon->ses" but some of them were replaces with a
> check for "server" instead.
>
> 150 shdr->Flags |= SMB2_FLAGS_SIGNED;
> 151 out:
> 152 return;
> 153 }
>
> regards,
> dan carpenter
--
Thanks,
Steve
From c8e3c17fd19c998423480cebe183eed2219685fa Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
Date: Sun, 31 May 2020 14:36:56 -0500
Subject: [PATCH] smb3: remove static checker warning
Remove static checker warning pointed out by Dan Carpenter:
The patch feeaec621c09: "cifs: multichannel: move channel selection
above transport layer" from Apr 24, 2020, leads to the following
static checker warning:
fs/cifs/smb2pdu.c:149 smb2_hdr_assemble()
error: we previously assumed 'tcon->ses' could be null (see line 133)
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
CC: Aurelien Aptel <aptel@xxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
---
fs/cifs/smb2pdu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 08728c0dcf8b..203a6bd55079 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -85,7 +85,7 @@ static const int smb2_req_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
int smb3_encryption_required(const struct cifs_tcon *tcon)
{
- if (!tcon)
+ if (!tcon || !tcon->ses)
return 0;
if ((tcon->ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA) ||
(tcon->share_flags & SHI1005_FLAGS_ENCRYPT_DATA))
--
2.25.1
